Eaton Corporation has added a hydro-mechanical torque control option and made several performance upgrades to its 420 open circuit hydraulic piston pump product line. The 420 pump with hydro-mechanical torque control automatically senses heavy loads and adjusts the hydraulic fluid flow accordingly. It is intended for moderate-flow, high-pressure mobile applications such as compact wheel loaders, rough terrain forklifts, telescopic booms, sweepers, backhoe loaders, and refuse trucks.
The 420 Series comes in a power dense design combining high pressure with small package size making it suitable for applications where space is at a premium. It comes in displacements ranging from 41cc to 80cc and can handle pressures of up to 275bar. Configurations are available to fit popular transmission and power take-off configurations.
To accommodate the new torque control feature, the pump housing was designed to decrease airborne noise to 76dBA at 1,800rpm and 207bar. A case-to-inlet check valve was added to improve cold weather operation and provide added protection to the seals and rotating group. The new torque control works in parallel with the standard compensator, using a special mechanism to replace the control piston. Eaton product manager, Todd McIntyre explains the reasoning behind this latest development.
“In compact and mid-size equipment, torque almost always needs to be controlled. Limiting the torque at the pump shaft across a wide range of engine speeds provides operators with the benefits of increased productivity, greater efficiency and fewer engine stalls. The result is lower engine emissions and improved fuel economy.
“Productivity is enhanced by increasing the speed with which the vehicle function is performed due to flow rate changes made by the torque control system. For example, raising a heavy load with a set of forks on a telescopic forklift (telehandler) places a significant amount of pressure on the hydraulic pump and system. To prevent engine stalls without limiting the telehandler’s lifting capacity, applications without the benefit of torque control would necessarily require a smaller displacement pump that significantly slows the operation of the forks. Torque control automatically senses heavy loads and adjusts flow accordingly.
“Limiting the flow in high pressure situations limits the torque the pump can apply to the engine and, as a result, avoids the corner horsepower point and prevents the engine from stalling. It also allows for higher flow and quicker operation when the set of forks is empty, which means higher productivity.”
And Mr McIntyre reminds readers that the substantial power density of Eaton’s 420 pumps is not compromised by the use of torque control.